1. Field of the Invention
The present invention relates to communication apparatuses capable of high frequency signal transmission, such as cordless phones and mobile phones, and methods of fabricating the same. More specifically the present invention relates to an improvement in a configuration for effectively shielding a radio frequency (RF) circuit module accommodated inside internal to such communication apparatuses.
2. Description of the Background Art
Conventionally, as disclosed for example in Japanese Patent Laying-Open No. 7-221822, cordless phones, mobile phones and other communication apparatuses accommodate a RF circuit module for processing signals to be transmitted and received. Such RF circuit module is mounted to a mother board. FIG. 9 is an exploded, perspective view of a typical RF circuit module and a perspective view of a mother board a. As shown in the figure, the RF circuit module is provided by integrally assembling a shielding frame b, a printed circuit board c accommodated in and held by frame b, and a pair of upper and lower shielding lids d and e closing the frame's upper and lower openings, respectively.
Frame b has protrusions b1 and notches b2 for holding printed circuit board c. Frame b also has four lower corners, each adjacent to a grounding tab b3 grounding mother board a.
Printed circuit boardchas a lower surface provided with grounding conductors c1 for grounding frame b, positionally corresponding to notch b2. To printed circuit board c are mounted a circuit pattern (not shown), adjustment components f for adjusting the communication apparatus's electrical performance, and connection terminals g allowing printed circuit board c to be electrically connected to mother board a.
Lids d and e each have an outer periphery provided with flaps d1 and e1, respectively, fitting into frame b downwards and upwards, respectively. Upper lid d has holes d2 allowing adjustment components f on printed circuit board c to be externally adjusted. Lower lid e has an opening e2 through which connection terminals g the printed circuit board pass.
In assembling the RF circuit module, printed circuit board c is initially inserted into frame b upwards until printed circuit board c abuts against protrusions b1. Then, as shown in FIG. 10, showing the frame's inside upwards, the notch's flap b4 is bent inwards. Thus printed circuit board cis held internal to frame b. Then flap b4 and grounding conductor c1 are soldered together, as shown in FIG. 10 with a dashed region A, to electrically connect grounding conductor c1 and flap b4 together. Then lids d and e are fit into frame b downwards and upwards, respectively. Thus, above adjustment components fare situated the upper lid's adjustment holes d2, while printed circuit board c has connection terminals g passing through the lower lid's opening e2 and thus protruding downwards. Thus, printed circuit board c has its outer periphery substantially entirely surrounded by frame b and lids d and e and thus shielded thereby.
When The RF circuit module thus fabricated has its frame's tabs b3 inserted into the mother board's mounting holes a1, the printed circuit board's connection terminals g are also simultaneously inserted into the mother board's terminal insertion holes a2. Thus the RF circuit module and mother board a are electrically connected together and integrally assembled.
As described above, a RF circuit module is configured of frame b, printed circuit board c and a pair of upper and lower lids d and e and fabricated by successively assembling such components.
For such type of module, there is a need for minimizing the number of components therefor to reduce the cost for them and to simplify its assembly process to reduce the cost for manufacturing the same.
Conventionally, however, nothing but the configuration as described above has in effect been applied to reliably shield the RF circuit module.